1. Field of the Invention
This invention relates to the field of sealing strips for expansion joints in concrete paving, and the like, and in particular, to reinforced sealing strips which lock themselves in position with and without the need for adhesives.
2. Description of the Prior Art
A reinforced sealing strip for expansion joints is disclosed in British Pat. No. 1,478,963--Bernardo and McManus. The sealing strip comprises a first compressible portion and a second longitudinal edge portion. The compressible portion comprises two hollow ribs, which may be provided with rigid reinforcing inserts. The strip is said to be useful for preformed grooves or for direct insertion into wet concrete. In the latter instance, however, it appears that the top portion of the groove must be wider, and accordingly, the preferred use seems to be in wet concrete. By way of contrast, the sealing strips taught herein do not require a specially shaped groove.
Among commercially popular sealing strips are those described in U.S. Pat. No. 3,718,403--Kerschner and U.S. Pat. No. 3,762,826--Bowman, the principal embodiment of each being substantially identical. The sealing strips described therein have the outline of a flattened chevron, and have flat side walls for engaging the concrete over a substantial surface area. Internal ribs define collapsible compartments, the ribs maintaining pressure against the side walls. Each specifically calls for the use of an adhesive which facilitates insertion and locks the sealing strip in place. Other configurations of sealing strips may be seen in U.S. Pat. No. 3,521,528--Wangerow, U.S. Pat. No. 3,899,260--Kerschner and U.S. Pat. No. 4,043,693--Brown. One embodiment of this invention avoids all of the problems connected with the use of internally collapsible structures by use of an elongated central core and a plurality of pairs of fins extending therefrom. This embodiment also shows that it is unnecessary for sealing joints to have large contact areas with the concrete, and notwithstanding the absence of such large contact areas, that the use of adhesives is unnecessary as well. This is a radical departure even from the reinforced sealing strip of British Pat. No. 1,478,963 which also relies on collapsible compartments, or in one embodiment, on expandable, initially evacuated compartments.
In the presently preferred adhesive-free embodiment, the sealing strip is locked into place by the forces exerted by two pairs of projecting fins, which are substantially deformed in the direction opposite insertion. It has been found that the fins not only exert pressure on the concrete, but exert pressure against one another through the central core. As a result, the sealing strip is firmly and securely locked into place. The principal seal at the top of the joint is formed by a smaller pair of fins, which are only slightly deformed as compared to to the locking fins. In the event there is a failure of the upper sealing fins, which are directed to keeping out debris the locking fins provide progressive backups. Removal of the sealing strip necessitates reversal of the locking fins entirely, which is extremely difficult.
Finally, the unitary structure of this embodiment, that is without internal ribs and compartments, particularly lends itself to simplified extruding processes, as compared to sealing strips heretofore available.
The other embodiment of this invention avoids most of the problems associated with the use of compartmented sealing strips, such as those shown in U.S. Pat. No. 3,521,528--Wangerow, by providing a reinforcing web embedded in the central vertical member. The twisting and stretching to which such sealing strips are ordinarily subjected during insertion, which weakens the seal, is substantially eliminated.